Fig. 2.

Resting and exercise test electrocardiograms. 12-lead surface electrocardiogram and subcutaneous implantable cardioverter-defibrillator (S-ICD) electrograms at rest (left) and during a treadmill exercise test (right). A – 12-lead surface electrocardiogram indicating new right bundle branch block during exercise (not present at rest). B – S-ICD electrogram from the primary sensing vector indicating a change in QRS-T wave morphology with exercise (similar to QRS-T wave morphology prior to the inappropriate shock, Fig. 1). C – S-ICD electrogram from the secondary sensing vector indicating that QRS-T wave morphology does not change significantly with exercise.